Viz wrote:Has anyone here experimented with UV filters on a digital body? I understand that some conversions are made by replacing the hot mirror over the sensor with a neutral substance rather than a specific graded one.. therefore allowing things such as UV experimentation.
If you use generic borosilicate glass it's transparent across a wide spectrum, but for the "CLR" conversion I offer I use Schott WG280 glass (which passes everything from 280nm upwards). 280nm is well into UV and is enough for most people.
Finding the best UV filter for your application can be tricky. Filters such as Hoya's U-330 let in light up to about 400nm (i.e. a band of UV) but then also let IR light in, so you need to combine these filters with IR-blocking filters. If you try to capture both UV and IR at once they'll usually not focus at the same point (think of it as an extreme form of chromatic aberration).
Also many lenses hardly pass any UV light at all... I think it's Bjorn who has info on his site about hand-grinding the UV-retarding coatings off a cheap lens. Specific UV lenses are
very expensive. Thus most people end up regarding UV photography as too hard...
I like the difference in PP methods - David here swaps channels, while Bjorn does a grey balance measurement..
Actually I think most people (myself included) start with with a white balance. Swapping channels is a step beyond that.
I would love it if someone uploaded any RAW file from any IR camera so we could see a few people's interpretations on colour corrections
Ok, not much sunshine today, but here's a photo I took with a PowerShot Pro1 (with internal RG715 "R72" filter) at Mungo NP last week.
DNG file (9 MB)
It's not a great photo in any way, but it's a starting point for your play.
ACR's range of colour temperatures doesn't seem to be as wide as some converters: this is the colour achieved by trying to balance off the dirt.
A bit of playing quickly achieved this:
Ok, over to you: what can you do with it?
I want to have a go in ACR calibration.
Normally "ACR calibration" refers to calibrating the colour behaviour using a Gretag-Macbeth ColorChecker target. What are you referring to?